Diesel fuel



Patented Nov. 22, 1938 DIESEL FUEL Robert G. Moran, Wenonah, and George S. Grandall, Woodbury, N. J., assignors to Socony- Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New York No Drawing. Application September 15, 1937, Serial N0. 163,913

8Claims.

This invention has to do in a general way with fuels for internal combustion engines of the Diesel type and is more particularly concerned with the modification of such fuels by the addition of 5 characterizing ingredients for the purpose of modifying or controlling the combustion characteristics.

In the Diesel cycle internal combustion engine where the fuel is injected into a combustion space it is important, to the attainment of maximum efficiency, that the delay period between injection and ignition be short. It will thus be seen that enhanced speed of ignition is a characteristic that is highly desirable. Improperly delayed ignition in a Diesel engine gives rise to the phenomena known as "knocking, due to improper coordination of combustion and cylinder condi-' tions. By decreasing the ignition relay period of Diesel fuel it ispossible to lower the compression pressure which will insure spontaneous ignition without combustion shock, thereby inin creasing the ease of starting and the smoothness with which combustion takes place. In this same connection, the low compression pressure permits of a lower weight in the engine and a lower cost per given power output.

It has been. found that the ignition quality of a fuel oil can be improved by the addition of small amounts of certain compounds which act as ignition accelerators. This offers a means for improving the better grades of Diesel fuels and a means of widening the range of available fuels by raising the ignition quality of lower grades to a point where they can be satisfactorily used.

A number of compounds have been proposed as ignition accelerators for Diesel fuels. Among such compounds are such materials as ethyl nitrate, amyl nitrite, and peroxides.

Many of these compounds are unsatisfactory from the standpoint of stability, cost, and toxicity.

Our present invention is directed to Diesel type fuels which have been improved in ignition quality by the addition of novel compounds which promote rapidity of combustion and so give the desired control of the combustion characteristics of the fuel.

By the term Diesel type fuels or Diesel .fuel as it is used herein we have reference not only to the distillates of the kerosene-like boiling range commonly denoted as Diesel fuel, but we intend to include, as well, the general field of hydrocarbon products, both heavier and lighter than the fuel above referred to, such, for example, as the light or heavy fuel oils and gasoline for use in Diesel cycle engines.

This invention is predicated upon our discovery of the fact that sulfurized terpene or sulfurized materials which are of predominantly 5 terpene composition, when added in minor proportions to Diesel fuel stocks, produce a blend of substantially improved ignition quality.

The additive ingredients contemplated by this invention do not lend themselves to definition by chemical formulae, nor can they be accurately defined as a mixture of specific chemical compounds. They can be prepared by thereaction of a terpen-e material, or a material predominantly terpene in composition (such as pine oil), with elementary sulfur, and are therefore termed, for purposes of description and definition herein, sulfurized terpenes.

sulfurized pine oil is an example of a preferred material illustrative of the type of additive ingredients contemplated by this invention. Pine oil, asis well known to those familiar withv the art, is a crude turpentine obtained by distillation of pine wood and is commercially available on the market. It is of predominantly terpene composition. The sulfurized pine oil" illustrative of this invention was prepared bytreating 400 cc. of pine oil with 146 grams of elementary sulfur and the mixture heated at approximately 150 C. for 2 hours. The product was then steam distilled up to a pot temperature of 175 C., the final product (bottoms from this distillation) having a specific gravity of 1.1609 and a sulfur contentof 36.84%.

In order to demonstrate the effectiveness of sulfurized terpenes as ignition accelerators for Diesel fuels, we have prepared a blended fuel from a sulfurized pine oil obtained according to the foregoing procedure, and have determined the ignition quality of such blended fuel by com- 40 parison with a. standard reference fuel in a converted C. F. R. engine, using the ignition delay method. The result obtained is expressed as a cetene number which is the per cent by volume of cetene in a blend of cetene and alphamethyl-naphthalene, which blended fuel has the same combustion characteristics as the sample being tested. (See Proc. Am. Soc. Testing Material, vol. 36, I p. 416 (1936).) An increase in cetene number indicates an improvement in fuel combustion characteristics.

The fuel blend, illustrative of our invention, was prepared by dissolving sulfurized pine oil in a petroleum distillate of the grade commonly known as No. 2 furnace oil, having a specific Concentration Cetene Increase in by weight N o. cetene N 0.

Percent sulfurized pine oil 2.0 58. 7.

sulfurized terpenes or sulfurized terpene materials of the type discussed above may be added to Diesel fuels in varying amounts depending on the quality of the base fuel stock and the extent to which it is desired to improve its ,ignition quality. They may be used, for example, in amounts up to 5.0%, but in general lower concentrations are preferred, and a concentration of 1.0% or 2.0% is believed to be sufficient for most purposes.

In the foregoing specification and in the following claims, the terms Diesel fuel, "hydrocarbon fuel oil", etc., include any and all types of hydrocarbon products intended for use in any engine operating according to the Diesel cycle.

We claim:

1. An improved Diesel fuel comprising: a hydrocarbon fuel oil and in admixture therewith a minor proportion of a. sulfurized terpene in an amount sufficient to decrease the ignition delay period of the fuel.

2. An improved Diesel fuel comprising: a hydrocarbon fuel oil and in admixture therewith a minor proportion of sulfurized pine oil in an amount suflicient to decrease the ignition delay period of the fuel.

' predominantly terpenes.

5. An improved Diesel fuel having in admixture therewith a minor proportion, sufficient to decrease the ignition delay period of the fuel, of a product of the type obtained by the interaction of elementary sulfur and a pine oil.

6. The method of preparing an improved Diesel fuel which includes: reacting a material of terpene composition with elementary sulfur to sulfurize said material; and adding a minor proportion of the sulfurized terpene product to a Diesel fuel stock in an amount sufficient to decrease the ignition delay period of the fuel.

7. The method of preparing an improved Diesel fuel which includes: reacting pine oil with elementary sulfur to sulfurize the same; and adding a minor proportion of the sulfurized pine oil to a Diesel fuel stock in an amount sufficient to decrease the ignition delay period of the blended fuel.

8. The method of accelerating the ignition of liquid fuels for internal combustion engines of the type wherein ignition of the fuel is spontaneously effected by injection into the compressed air in the engine cylinder, which comprises admixing with the fuel, prior to ignition, a minor proportion of sulfurized pine oil.

ROBERT C. MORAN. GEORGE S. CRANDALL. 

